Handwriting pen



FIG. 1 is a front elevation view of a handwriting pen showing my new design;

FIG. 2 is a back elevation view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is an enlarged top plan view thereof; and,

FIG. 6 is an enlarged bottom plan view thereof.

The broken lines in the drawings illustrate portions of the handwriting pen and form no part of the claimed design. 

CLAIM The ornamental design for a handwriting pen, as shown and described. 